Question:
The work function of three photosensitive materials are: Sodium (2.75 eV), copper (4.65 eV) and gold (5.1 eV). Which of the following statements is correct (Visible light range: $4 \times 10^{14}$ Hz to $8 \times 10^{14}$ Hz)?
The work function of three photosensitive materials are: Sodium (2.75 eV), copper (4.65 eV) and gold (5.1 eV). Which of the following statements is correct (Visible light range: $4 \times 10^{14}$ Hz to $8 \times 10^{14}$ Hz)?
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Higher work function ⇒ higher required frequency.
Updated On: May 1, 2026
- Copper and gold
- Sodium
- All with IR
- All with visible
- None
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Verified By Collegedunia
The Correct Option is B
Solution and Explanation
Concept:
Photoelectric condition:
\[
h\nu \ge \phi
\]
Step 1: Convert work function \[ 2.75 \times 1.6\times10^{-19} = 4.4\times10^{-19} J \]
Step 2: Threshold frequency \[ \nu_0 = \frac{4.4\times10^{-19}}{6.63\times10^{-34}} \approx 6.6\times10^{14} \]
Step 3: Compare Visible range ends near this value ⇒ needs UV. \[ \boxed{\text{Only sodium works}} \]
Step 1: Convert work function \[ 2.75 \times 1.6\times10^{-19} = 4.4\times10^{-19} J \]
Step 2: Threshold frequency \[ \nu_0 = \frac{4.4\times10^{-19}}{6.63\times10^{-34}} \approx 6.6\times10^{14} \]
Step 3: Compare Visible range ends near this value ⇒ needs UV. \[ \boxed{\text{Only sodium works}} \]
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